The present invention relates to a shielding connector, and more particularly to a shielding connector including a dielectric body which receives inner conductor terminals connected to core-wire terminal parts of a shielded cable, and a shielding shell applied to the outer periphery of the dielectric body.
A conventional shielding connector 110 is constructed as shown in FIGS. 4 and 5. In a shielded cable 100, core wires 101 each including a conductor 101a covered with an insulating layer 101b, and a drain wire 102 including a plurality of twisted steel element wires are covered with a metal foil 103. The outer periphery of the metal foil is covered with an insulating covering 104. The core wires 101 and the drain wire 102 are expose at a terminal part of the shielded cable 100. The terminal parts of those exposed wires, the core wires 101 and the drain wire 102, are connected to an inner conductor terminal 120 and a drain terminal 130, respectively. The inner conductor terminal 120 and the drain terminal 130 are placed in a terminal receptacle 141 of a dielectric body 140. A metal shielding shell 150 electrically conductively connected to the drain terminal 130 is applied to the outer periphery of the dielectric body 140.
As seen from FIG. 5 showing a cross sectional view taken on line Axe2x80x94A in FIG. 4, the shielded cable 100 is connected to the shielding connector 110 in the following manner. The inner conductor terminals 120 and the drain terminal 130 are first put in the terminal receptacle 141 of the dielectric body 140. Then, the shielding shell 150 is set around the dielectric body to thereby assemble the shielding connector 110. The exposed core wires 101 of the shielded cable 100 are press connected to press-connection blades 121L and 121R, which stand erect, while being opposed, in a rear part of the inner conductor terminal 120. The drain wire 102 is press connected to press-connection blades 131L and 131R, and 132L and 132R, which stand erect, while being opposed, in a rear part of the drain terminal 130 (the drain wire and the drain terminal are not directly shown, but are parenthesized in the figure). The terminal part of the insulating covering 104 of the shielded cable 100 is adhesively held with insulating barrels 151L and 151R provided at the rear end of the shielding shell 150.
To connect the shielded cable containing a plurality of core wires (inclusive of the drain wire) to the shielding connector, as shown in FIG. 4, the core wire located closer to the outer side of the cable must be bent to position the wire at its connection position to the inner conductor terminal. To this end, such a distance as to allow the core wire to bend must be secured over a range from the base part of the core wire to the connection part. As a result, as shown in FIG. 5, a gap (space) C is present between the terminal parts of the exposed core wires and the inner bottom surface of the shielding shell.
In a state that the core wires are not exposed, a part of each core wire shielded by the metal foil serves as a signal transmission line. When the metal foil is peeled off parts of the core wires to expose those parts, a signal leaks from the exposed parts of the core wires, viz., a cross sectional configuration of the signal transmission line, varies. If a space is present between the exposed parts of the core wires and the inner bottom surface of the shielding shell, a cross sectional configuration of the signal transmission line is greatly varied correspondingly. As a result, a value shift of impedance occurs between the exposed part of the core wire and the not exposed part of the core wire. In the shielding connector used as a high speed signal transmission interface, such as USB (universal serial bus) and IEEE1394, if such an impedance shift occurs, an abnormal signal or noise is generated at the impedance mismatching part, possibly resulting in an system error or the like. For this reason, an exact impedance matching is required between the interface and the printed circuit board (PCB).
Accordingly, an object of the present invention is to provide a shielding connector which reduces an impedance variation (value shift) appearing between the exposed terminal parts of the core wires of the shielded cable, which are at the connection part of the shielded cable to the shielding connector, and the not exposed part of the shielded cable, the impedance variation being due to a variation of the cross sectional configuration of the signal transmission line, thereby improving a reliability of the signal transmission line.
According to the present invention, there is provided a shielding connector having inner conductor terminals to which terminal parts of core wires of a shielded cable, a dielectric body for receiving the inner conductor terminals, and a shielding shell installed around the dielectric body, wherein an insulating plate for suppressing an impedance variation caused by a variation of a cross sectional configuration of a signal transmission line, which results from the exposure of the terminal parts of the core wires, is interposed between the terminal parts of the core wires connected to the inner conductor terminals and a inner bottom surface of the shielding shell put around the dielectric body.
In the shielding connector thus constructed, the insulating plate is located in a space present between the exposed core wires connected to the inner conductor terminals and an inner bottom surface of the shielding shell. With provision of the dielectric body, the space is reduced, and hence, a variation of a cross sectional configuration of the exposed parts of the core wires as a signal transmission line is reduced. As a result, an impedance variation within the shielding connector is reduced. And generation of abnormal signals and noise when signals are transmitted is effectively suppressed.
The insulating plate is interposed between the exposed parts of the core wires and the inner bottom surface of the shielding shell. With this feature, if the insulating covering of the core wire is broken by some cause and the conductor of the core wire is exposed, there is no chance that the exposed conductor comes in contact with the shielding shell and shortcircuiting occurs therebetween. As a result, a stable connection state is ensured between the shielded cable and the shielding connector.
The insulating plate is preferably provided integrally with the dielectric body. If the insulating plate is so formed, the number of required parts and the number of production process steps are reduced. Therefore, the efficiency of producing the whole shielding connector is improved.